Guernsey, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.8 °F (low) to 58.9 °F (high). Annual precipitation averages 37.3 Inches. Guernsey is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.7 °F | 28.4 °F | 1.12 in. |
| February | 15.2 °F | 33.2 °F | 1.38 in. |
| March | 26.3 °F | 46.3 °F | 2.14 in. |
| April | 37.5 °F | 59.9 °F | 3.68 in. |
| May | 50.1 °F | 71.3 °F | 4.83 in. |
| June | 61.0 °F | 81.2 °F | 5.39 in. |
| July | 63.9 °F | 84.6 °F | 4.3 in. |
| August | 61.3 °F | 82.7 °F | 4.36 in. |
| September | 52.3 °F | 75.8 °F | 3.57 in. |
| October | 40.2 °F | 62.7 °F | 2.87 in. |
| November | 28.2 °F | 47.0 °F | 2.11 in. |
| December | 17.9 °F | 34.1 °F | 1.54 in. |
| Annual | 38.8 °F | 58.9 °F | 37.29 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |